library and require load and attach add-on packages.
library(package, help, pos = 2, lib.loc = NULL, character.only = FALSE, logical.return = FALSE, warn.conflicts = TRUE, quietly = FALSE, verbose = getOption("verbose"))
require(package, lib.loc = NULL, quietly = FALSE, warn.conflicts = TRUE, character.only = FALSE)character.only is FALSE (default) or
TRUE).search().NULL. The default value
of NULL corresponds to all libraries currently known to
.libPaths().
Non-existent library trees are silently ignored.package or
help can be assumed to be character strings.TRUE, FALSE or
TRUE is returned to indicate success.TRUE, warnings are
printed about conflicts from attaching the new
package. A conflict is a function masking a function,
or a non-function masking a non-function.
TRUE, additional diagnostics are
printed.TRUE, no message confirming
package attaching is printed, and most often, no errors/warnings are
printed if package attaching fails.library returns (invisibly) the list of attached
packages, but TRUE or FALSE if logical.return is
TRUE. When called as library() it returns an object of
class "libraryIQR", and for library(help=), one of
class "packageInfo".require returns (invisibly) a logical indicating whether the required
package is available.
getOption("checkPackageLicense") == TRUE, then at first
use of a package with a not-known-to-be-FOSS (see below) license the
user is asked to view and accept the license: a list of accepted
licenses is stored in file ‘~/.R/licensed’. In a non-interactive
session it is an error to use such a package whose license has not
already been accepted. Free or Open Source Software (FOSS, e.g.,
http://en.wikipedia.org/wiki/FOSS) packages are determined by
the same filters used by available.packages but applied
to just the current package, not its dependencies. There can also be a site-wide file ‘R_HOME/etc/licensed.site’ of
packages (one per line).library takes some further actions when package methods
is attached (as it is by default). Packages may define formal generic
functions as well as re-defining functions in other packages (notably
base) to be generic, and this information is cached whenever
such a namespace is loaded after methods and re-defined functions
(implicit generics) are excluded from the list of conflicts.
The caching and check for conflicts require looking for a pattern of
objects; the search may be avoided by defining an object
.noGenerics (with any value) in the namespace. Naturally, if the
package does have any such methods, this will prevent them from
being used.library(package) and require(package) both load the
namespace of the package with name package and attach it on the
search list. require is designed for use inside other
functions; it returns FALSE and gives a warning (rather than an
error as library() does by default) if the package does not
exist. Both functions check and update the list of currently attached
packages and do not reload a namespace which is already loaded. (If
you want to reload such a package, call detach(unload =
TRUE) or unloadNamespace first.) If you want to load a
package without attaching it on the search list, see
requireNamespace. To suppress messages during the loading of packages use
suppressPackageStartupMessages: this will suppress all
messages from R itself but not necessarily all those from package
authors.
If library is called with no package or help
argument, it lists all available packages in the libraries specified
by lib.loc, and returns the corresponding information in an
object of class "libraryIQR". The structure of this class may
change in future versions. In earlier versions of R, only the names
of all available packages were returned; use .packages(all =
TRUE) for obtaining these. Note that
installed.packages()
returns even more information.
library(help = somename) computes basic information about the
package somename, and returns this in an object of class
"packageInfo". The structure of this class may change in
future versions. When used with the default value (NULL) for
lib.loc, the attached packages are searched before the libraries.
.libPaths, .packages. attach, detach, search,
objects, autoload,
requireNamespace,
library.dynam, data,
install.packages and
installed.packages;
INSTALL, REMOVE.
The initial set of packages attached is set by
options(defaultPackages=): see also Startup.
library() # list all available packages
library(lib.loc = .Library) # list all packages in the default library
library(help = splines) # documentation on package 'splines'
library(splines) # attach package 'splines'
require(splines) # the same
search() # "splines", too
detach("package:splines")
# if the package name is in a character vector, use
pkg <- "splines"
library(pkg, character.only = TRUE)
detach(pos = match(paste("package", pkg, sep = ":"), search()))
require(pkg, character.only = TRUE)
detach(pos = match(paste("package", pkg, sep = ":"), search()))
require(nonexistent) # FALSE
## Not run:
# ## if you want to mask as little as possible, use
# library(mypkg, pos = "package:base")
# ## End(Not run)Run the code above in your browser using DataLab